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Feuille d’exercices : maths du métier

Twelve problems of the arithmetic that fills a working day: fractions to decimals, a decimal to the nearest sixteenth, inches to millimetres and back, a percent allowance on a wire order, a diagonal from two sides, and the area of a round hole. The key shows the working on every one.

Trade math worksheet · sheet #1

NomDateScore/ 12

fraction → decimal: top ÷ bottomnearest 1/16: × 16, round, over 161 in = 25,4 mmc = √(a² + b²)circle: π × r²

  1. Write 5/8″ as a decimal.

  2. A drawing says 1.06″. What is that to the nearest sixteenth?

  3. Convert 26 inches to millimetres.

  4. Convert 2,950 mm to inches (two decimals).

  5. Allow 30% extra on 200 ft of wire. How many feet is the allowance?

  6. A run goes 20 ft across and 23 ft up. How long is the diagonal, to two decimals?

  7. What is the area of a 6 in circle (a knockout or a core hole), to two decimals?

  8. Write 15/16″ as a decimal.

  9. A drawing says 11.47″. What is that to the nearest sixteenth?

  10. Convert 24 inches to millimetres.

  11. Convert 460 mm to inches (two decimals).

  12. Allow 12% extra on 180 ft of wire. How many feet is the allowance?

sparkytools.net/worksheets/trade-math — free practice sheet. Practice numbers only; nothing here is a code-book value.

Answer key · Trade math worksheet · sheet #1

Show the answers and the working
  1. 0,625″ 5/8 = 10/16 = 10 ÷ 16 = 0,625
  2. 1 1/16″ 1.06 × 16 = 16.96 → 17 sixteenths = 1 1/16″
  3. 660,4 mm 26 × 25,4 = 660,4 mm
  4. 116,14″ 2 950 ÷ 25,4 = 116,14″
  5. 60 ft 30 ÷ 100 × 200 = 60 ft (order 260 ft)
  6. 30,48 ft √(20² + 23²) = √(400 + 529) = √929 = 30,48 ft
  7. 28,27 in² π × r² = 3.1416 × 3² = 28.27 in²
  8. 0,9375″ 15/16 = 15/16 = 15 ÷ 16 = 0,9375
  9. 11 1/2″ 11.47 × 16 = 183.52 → 184 sixteenths = 11 1/2″
  10. 609,6 mm 24 × 25,4 = 609,6 mm
  11. 18,11″ 460 ÷ 25,4 = 18,11″
  12. 21,6 ft 12 ÷ 100 × 180 = 21.6 ft (order 201.6 ft)

How to use it

  1. Print the sheet (or save it as a PDF from the print dialog). The answer key prints on its own page, so you can hand the sheet out and keep the key.
  2. Work every problem on paper, with the formula strip at the top, before you look at anything.
  3. Mark it from the key. For each miss, read the working line and find the exact step you did differently.
  4. Press New sheet for another twelve; the sheet number is in the link, so the same sheet can be printed again.

Worked example

A decimal to the nearest sixteenth

  1. A print says 7.43″. Your tape reads in sixteenths.
  2. Take the whole inches off: 7, and 0.43 left.
  3. 0.43 × 16 = 6.88, which rounds to 7 — so 7/16.
  4. The mark is 7 7/16″. Check: 7/16 = 0.4375, within a hair of 0.43.

Rounding to the nearest sixteenth is never more than 1/32″ out — about 0.8 mm.

Questions fréquentes

Why sixteenths?

Because most tapes are marked in them and most field work is measured to them. Finer work goes to thirty-seconds; the method is the same with 32 in place of 16.

Can I print a different sheet?

Yes. Press New sheet and you get another twelve problems with their own answer key; the sheet number goes into the link, so you can print it again later or send it to someone and they get the same sheet. Sheet #1 is always the one this page opens on.

Does it cost anything or need an account?

No. Every worksheet is free, prints from your own browser (or saves as a PDF from the print dialog), and needs no sign-up.

Voir aussi

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