MWALA_LEARN-LOGARITHM-TABLE

Objectives: Mathematical Tables - Logarithms

Mathematical Tables - Logarithms (Page 1)

Mathematical Tables
Common Logarithms of Numbers (Page 1)

x log10x or log x Mean Differences (Add)
0123456789 12345678910
1.00.00000.00430.00860.01280.01700.02120.02530.02940.03340.0374491317212630343843
1.10.04140.04530.04920.05310.05690.06070.06450.06820.07190.0755481216202428323640
1.20.07920.08280.08640.08990.09340.09690.10040.10380.10720.1106371114182225293336
1.30.11390.11730.12060.12390.12710.13030.13350.13670.13990.143036913161922252831
1.40.14610.14920.15230.15530.15840.16140.16440.16730.17030.173236912151821242730
1.50.17610.17900.18180.18470.18750.19030.19310.19590.19870.201436911141720232629
1.60.20410.20680.20950.21220.21480.21750.22010.22270.22530.227935811141720222528
1.70.23040.23300.23550.23800.24050.24300.24550.24800.25040.252935811141619222427
1.80.25530.25770.26010.26250.26480.26720.26950.27180.27420.276525710131518202325
1.90.27880.28100.28330.28560.28780.29000.29230.29450.29670.30102579121416192123
2.00.30100.30320.30540.30750.30960.31180.31390.31600.31810.32012469111315171921
2.10.32220.32430.32630.32840.33040.33240.33450.33650.33850.34042468101214161820
2.20.34240.34440.34640.34830.35020.35220.35410.35600.35790.35982468101214151719
2.30.36170.36360.36550.36740.36920.37110.37290.37470.37660.3784246791113151719
2.40.38020.38200.38380.38560.38740.38920.39100.39270.39450.3962245791113141618
2.50.39790.39970.40140.40310.40480.40650.40820.40990.41160.4133235791012141617
2.60.41500.41660.41830.42000.42160.42320.42490.42650.42810.4298235781012131517
2.70.43140.43300.43460.43620.43780.43930.44090.44250.44400.4456135681011131516
2.80.44720.44870.45020.45180.45330.45480.45640.45790.45940.460913468911131416
2.90.46240.46390.46540.46690.46830.46980.47130.47280.47420.475713467910121315
3.00.47710.47860.48000.48140.48290.48430.48570.48710.48850.490013457810111314
3.10.49140.49280.49420.49550.49690.49830.49970.50110.50240.50381245789111214
3.20.50510.50650.50790.50920.51050.51190.51320.51450.51590.51721245689111213
3.30.51850.51980.52110.52240.52370.52500.52630.52760.52890.53021235679101113
3.40.53150.53280.53400.53530.53660.53780.53910.54030.54160.5428123467891112
3.50.54410.54530.54650.54780.54900.55020.55140.55270.55390.5551123457891011
3.60.55630.55750.55870.55990.56110.56230.56350.56470.56580.567012345678910
3.70.56820.56940.57050.57170.57290.57400.57520.57630.57750.578612345678910
3.80.57980.58090.58210.58320.58430.58550.58660.58770.58880.590012345678910
3.90.59110.59220.59330.59440.59550.59660.59770.59880.59990.601012345678910
Mathematical Tables - Logarithms (Page 2)

Mathematical Tables
Common Logarithms of Numbers (Page 2)

x log10x or log x Mean Differences (Add)
0123456789 12345678910
4.00.60210.60310.60420.60530.60640.60750.60850.60950.61060.61171234567899
4.10.61280.61380.61490.61590.61700.61800.61910.62010.62120.62221234567899
4.20.62320.62430.62530.62630.62740.62840.62940.63040.63140.63251234567899
4.30.63350.63450.63550.63650.63750.63850.63950.64050.64150.64251234567899
4.40.64350.64440.64540.64640.64740.64840.64940.65030.65130.65231234567899
4.50.65320.65420.65520.65610.65710.65800.65900.65990.66090.66181234567899
4.60.66280.66370.66460.66560.66650.66740.66840.66930.67020.67121234567899
4.70.67210.67300.67400.67490.67580.67670.67760.67860.67950.68041234567899
4.80.68120.68210.68300.68390.68480.68560.68650.68740.68830.68921234567899
4.90.69020.69100.69190.69280.69370.69460.69550.69640.69720.69811234567899
5.00.69900.69980.70060.70160.70230.70310.70380.70460.70540.70621234567899
5.10.70700.70780.70860.70930.71000.71080.71150.71230.71300.71381234567899
5.20.71450.71520.71590.71660.71730.71800.71870.71940.72010.72081234567899
5.30.72150.72220.72290.72360.72430.72500.72560.72630.72700.72771234567899
5.40.72840.72910.72980.73040.73110.73180.73240.73310.73380.73441234567899
5.50.73510.73570.73640.73700.73770.73830.73900.73960.74030.74091234567899
5.60.74150.74210.74280.74340.74400.74460.74520.74580.74640.74701234567899
5.70.74750.74810.74870.74930.74990.75050.75110.75170.75230.75281234567899
5.80.75340.75400.75450.75510.75570.75630.75680.75740.75800.75851234567899
5.90.75910.75960.76020.76080.76140.76190.76250.76300.76360.76421234567899
6.00.76470.76530.76580.76640.76690.76750.76800.76860.76910.76971234567899
6.10.77020.77080.77130.77190.77240.77300.77350.77410.77460.775212345678910
6.20.79240.79290.79350.79400.79450.79510.79560.79610.79660.797212345678910
6.30.79930.79980.80030.80080.80130.80180.80230.80280.80330.803812345678910
6.40.80620.80670.80720.80770.80820.80870.80920.80970.81020.810712345678910
6.50.81220.81270.81320.81370.81420.81470.81520.81570.81620.816612345678910
6.60.81950.82000.82040.82090.82140.82190.82230.82280.82330.823712345678910
6.70.82610.82650.82700.82740.82790.82830.82880.82920.82970.830112345678910
6.80.83250.83290.83330.83370.83420.83460.83500.83540.83580.836212345678910
6.90.83880.83920.83960.84000.84040.84080.84120.84160.84200.842412345678910
7.00.84510.84550.84590.84630.84670.84710.84750.84790.84830.848712345678910
7.10.85130.85170.85200.85240.85280.85320.85360.85400.85430.854712345678910
7.20.85730.85760.85800.85840.85880.85910.85950.85990.86030.860612345678910
7.30.86330.86370.86400.86440.86480.86510.86550.86590.86620.866612345678910
7.40.86920.86960.86990.87030.87060.87100.87130.87170.87200.872412345678910
7.50.87510.87540.87570.87610.87640.87670.87710.87740.87780.878112345678910
7.60.88020.88050.88090.88120.88150.88190.88220.88250.88290.883212345678910
7.70.88650.88680.88710.88750.88780.88810.88840.88880.88910.889412345678910
7.80.89210.89240.89270.89300.89330.89360.89390.89420.89450.894812345678910
7.90.89760.89790.89820.89850.89880.89910.89940.89970.90000.900312345678910
Mathematical Tables - Logarithms (Page 3)

Mathematical Tables
Common Logarithms of Numbers (Page 3)

x log10x or log x Mean Differences (Add)
0123456789 12345678910
8.00.90310.90360.90420.90470.90530.90580.90630.90690.90740.90791233445567
8.10.90850.90900.90950.91010.91060.91120.91170.91230.91280.91331223344556
8.20.91380.91430.91490.91540.91600.91650.91700.91760.91810.91861223344556
8.30.91910.91960.92010.92060.92120.92170.92220.92280.92330.92381223344556
8.40.92430.92480.92530.92580.92620.92670.92720.92780.92830.92881223344556
8.50.92940.92990.93040.93090.93140.93180.93230.93280.93330.93381223334455
8.60.93450.93490.93540.93590.93640.93690.93740.93780.93830.93881223334455
8.70.93950.94000.94050.94090.94140.94190.94240.94280.94330.94381223334455
8.80.94450.94490.94540.94590.94640.94680.94730.94780.94820.94871222334445
8.90.94940.94990.95030.95080.95130.95170.95220.95270.95310.95361222334445
9.00.95420.95460.95510.95560.95600.95650.95700.95740.95790.95831222334445
9.10.95860.95900.95950.96000.96040.96090.96130.96180.96220.96271122333445
9.20.96300.96340.96390.96430.96480.96520.96560.96610.96650.97001122233444
9.30.96850.96890.96940.96980.97030.97070.97120.97160.97210.97251122233344
9.40.97300.97340.97390.97430.97470.97520.97560.97610.97650.97691122233344
9.50.97720.97770.97810.97860.97900.97940.97980.98030.98070.98111122233344
9.60.98140.98190.98230.98270.98310.98350.98400.98440.98480.98521122233344
9.70.98560.98600.98640.98680.98720.98760.98800.98840.98880.98921122233344
9.80.98950.99000.99040.99080.99120.99160.99200.99240.99280.99321122233344
9.90.99370.99410.99450.99490.99530.99570.99610.99650.99690.99731122233344

Example: log10 9.592 = 0.9819

HOW TO MAKE & USE COMMON LOG TABLES (Form 2 friendly)

Common Logarithm (base-10) Tables — How to BUILD and USE

Designed for Form 2 • Very simple language • English + Kiswahili

1) What is a “common log”?

English: It is a number that tells how many tens make another number. We write log x or log₁₀x.

Kiswahili: Ni nambari inayoonyesha ni mara ngapi tunazidisha kwa 10 ili kupata nambari nyingine. Tunaandika log x au log₁₀x.

2) Characteristic & Mantissa

Characteristic = whole-number part (can be negative). Mantissa = decimal part (always between 0 and 1). Example: log 250 = 2.3979 → characteristic = 2, mantissa = 0.3979.

Characteristic ni sehemu ya mzima (inaweza kuwa hasi). Mantissa ni sehemu ya desimali (kati ya 0 na 1). Mfano: log 250 = 2.3979 → characteristic = 2, mantissa = 0.3979.

Your printed table stores ONLY the mantissa for 1.00–9.99.

3) Table layout

  • Rows: 1.0, 1.1, 1.2, …, 9.9
  • Columns: 0–9 → gives 1.20, 1.21, … etc.
  • Mean Differences (Add): tiny numbers that adjust for a fourth digit.

Safu (rows), nguzo (columns), na “Mean Differences” = marekebisho madogo kwa tarakimu ya nne.

A. Super-easy rules you will memorize (no advanced math)

A1) Laws to remember
  • Add for ×: log(AB)=logA + logB
  • Ukizidisha, ongeza logi: log(AB)=logA + logB
  • Subtract for ÷: log(A/B)=logA − logB
  • Ukiigawa, toa logi: log(A/B)=logA − logB
  • Powers: log(Aⁿ)=n·logARoots: log(ⁿ√A)=logA / n
  • Nguli/Mizizi: log(Aⁿ)=n·logA, log(ⁿ√A)=logA / n
A2) Seed values to memorize (4 d.p.)
log2 = 0.3010
log3 = 0.4771
log4 = 0.6021
log5 = 0.6990
log6 = 0.7782
log7 = 0.8451
log8 = 0.9031
log9 = 0.9542

Hizi nane ukizikamata kichwani, unaweza kujenga karibu jedwali lote.


A3) “+0.01 step rule” (very handy for rows)

When x goes up by 0.01, the mantissa grows by about Δ ≈ 0.004343 / x. (Just divide 0.004343 by the current row number.)

Ukitoka x kwenda x+0.01, ongezeko la mantissa takribani Δ ≈ 0.004343 / x. Gawa tu 0.004343 kwa thamani ya safu x.

Example: around row x=1.50, add about 0.004343/1.50 ≈ 0.0029 each column step.
Mfano: karibu na x=1.50, ongeza ~0.0029 kwa kila kolamu (1.50→1.51→1.52…).
A4) Mean Differences (Add)

They tell how much to add for a fourth digit. If you are at 2.73 and the next digit is 6 (so 2.736), add the small number listed under 6 in the Mean Difference block of that row.

Zinaonyesha kiasi cha kuongeza kwa tarakimu ya nne. Ukiwa 2.73 na tarakimu inayofuata ni 6 (yaani 2.736), ongeza namba ndogo iliyo chini ya 6 kwenye sehemu ya “Mean Differences”.

B. HOW TO USE a common-log table (step by step)

1
Normalize the number so it sits between 1 and 10: write N = s × 10ᵏ with 1 ≤ s < 10.
Badilisha namba iwe N = s × 10ᵏ ambapo 1 ≤ s < 10.
2
Characteristic is k. (If the number is less than 1, k is negative.)
Characteristic ni k. (Chini ya 1 → hasi.)
3
Mantissa: row = first two significant digits (with a decimal); column = third digit; for a 4th digit add the Mean Difference.
Mantissa: safu = tarakimu mbili za mwanzo, kolamu = tarakimu ya tatu; ya nne tumia Mean Difference.
4
Add them: log N = k + mantissa.
Ongeza: log N = k + mantissa.
Quick example: Find log 9.592.
Row 9.5, column 9 gives 0.9818 (approx). 4th digit is “2” → add MD under 2 → 0.9819. Characteristic 0 → answer 0.9819.
Mfano wa haraka: Safu 9.5, kolamu 9; ongeza MD ya “2” → 0.9819. Hivyo jibu 0.9819.

C. HOW TO BUILD the table yourself (Form-2 friendly plan)

C1) Build anchor points (easy to memorize)
  • Memorize the 8 seed logs in section A2. From them you also get:
    • log 1.5 = log3 − log2 = 0.4771 − 0.3010 = 0.1761
    • log 2.5 = log5 − log2 = 0.6990 − 0.3010 = 0.3980 (≈ 0.3979 in tables)
    • log 7.5 = log(15/2) = log15 − log2 = (0.1761+0.9999) − 0.3010 ≈ 0.8751 (close to 0.8751)
  • Kumbuka hizo 8; kisha tumia kuzidisha/kugawa kupata 1.5, 2.5, 3.5, … kama mifano hapo juu.
C2) Fill a whole row with the “+0.01 step rule”
Example: Row 1.5 (build 1.50 → 1.59)
  1. Start value: log 1.50 = 0.1761.
  2. Step size: Δ ≈ 0.004343 / 1.50 ≈ 0.0029.
  3. Add repeatedly (update x each time). Round to 4 dp:
    • 1.51: 0.1761 + 0.0029 ≈ 0.1790
    • 1.52: +0.0029 ≈ 0.1819
    • … continue to get 1.59 ≈ 0.2014

These match the printed table very closely.

Example: Row 8.0 (8.00 → 8.09)
  1. Anchor: log 8 = 0.9031.
  2. Step: Δ ≈ 0.004343 / 8.00 ≈ 0.00054.
  3. Add up to column 9: 0.9031, 0.9036, 0.9042, … → matches standard row 8.0.

Kila mara zungusha hadi sehemu 4 za desimali.

C3) Make the “Mean Differences (Add)”

For any row entry (say 1.53 to 1.54), find the change in mantissa between adjacent columns (e.g., 0.1818 → 0.1847 = increase of 0.0029 = 29 in the 4th decimal place). Distribute that increase across digits 1–9. A quick way is:

Step in last place ≈ round(10⁴ × [log(x+0.01) − log(x)])
MD for digit d = round(d × step) − round((d−1) × step)

Tafuta tofauti kati ya kolamu mbili zilizo karibu; geuza kuwa “tarakimu ya mwisho” (mfano 0.0029 → 29). Gawa sawasawa kwa tarakimu 1–9 ukitumia kanuni hapo juu; haya ndiyo “Mean Differences”.

C4) Finish all rows
  • Repeat C1–C3 for rows 1.0 → 9.9. The step Δ slowly changes because x changes; recalc it or peek at the last two entries to keep your row smooth.
  • Rudia hatua hizo kwa safu zote. Kumbuka Δ hubadilika taratibu kadri x inavyobadilika.

D. Real-life, vivid uses (kujifunzia haraka)

1) Sound (Decibels)

Level L = 10 log(I/I₀). If sound intensity becomes 100×, add 10·log(100)=20 dB.

Ukiongeza nguvu mara 100, unaongeza 20 dB. Tumia jedwali kupata logi ndogo ndogo.

2) pH in Chemistry

pH = −log[H⁺]. If [H⁺]=3.2×10⁻⁴, log = −(−4 + mantissa of 3.2) = 4 − 0.5051 → pH ≈ 3.49.

Mantissa ya 3.2 (safu 3.2) kisha ongeza characteristic 4 → pH ≈ 3.49.

3) Fast multiplication

To multiply 2.73 × 6.8: add logs (0.4362 + 0.8325 ≈ 1.2687) → antilog gives ≈ 18.6.

Zidisha kwa kujumlisha logi kisha rudi kwenye namba (antilog) → ≈ 18.6.

4) Growth & interest

Estimate 1.07¹⁰: 10·log(1.07) ≈ 0.2938 → antilog ≈ 1.96.

Ukuaji wa 7% kwa miaka 10 ≈ 1.96 (karibu mara mbili).

E. Practice drills (for memory & speed)

  1. Recall seeds daily: 0.3010, 0.4771, 0.6021, 0.6990, 0.7782, 0.8451, 0.9031, 0.9542. Zikariri kwa sauti.
  2. Row builder: pick a row (e.g., 2.3). Use an anchor near it (2=0.3010, 2.5≈0.3980) then the +0.01 step rule to fill columns 0–9.
  3. Mean differences: compute one cell’s step (difference × 10⁴), split across digits 1–9.
  4. Use the table: do 5 quick logs and 5 quick antilogs daily.

F. Pocket cheatsheet

  • Normalize: N = s × 10ᵏ, 1 ≤ s < 10
  • Row = first 2 significant digits, Column = 3rd, add MD for 4th
  • log N = k + mantissa
  • Antilog: match mantissa in table → place decimal using k
  • Build rows: start from anchor, add Δ ≈ 0.004343/x, round to 4 d.p.

Jenga safu: anza na thamani ya karibu, ongeza Δ ≈ 0.004343/x, zungusha hadi sehemu 4.

Reference Book: N/A

Author name: SIR H.A.Mwala Work email: biasharaboraofficials@gmail.com
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