Chapter 13.5 (Mathematics 5)

Arithmethic with Time. Multiplication 

Multiplication of Minutes and Seconds by Whole Numbers

In groups of five:

  1. Write a period of time in minutes and seconds.
  2. Multiply the time by a whole number less than 10.
  3. Write the product in minutes and seconds.
  4. Discuss the process of multiplying time in minutes and seconds by whole numbers. Share the results with other groups.

Example 5a

Multiply 16 minutes 15 seconds × 3

minutes seconds 16 15 × 3 48 45

Example 5b

Multiply 7 minutes 36 seconds × 2

minutes seconds 7 36 × 2 15 12

  1. 36 seconds × 2 = 72 seconds
  2. Regroup 72 into 1 minute 12 seconds
  3. 7 minutes × 2 = 14 minutes
  4. 14 minutes + 1 minutes = 15 minutes

Exercise G

a) minutes seconds 15 23 × 2

b) minutes seconds 26 12 × 4

c) minutes seconds 36 15 × 3

a) minutes seconds 5 18 × 4

b) minutes seconds 12 24 × 5

c) minutes seconds 15 32 × 6

If the answer is 0, leave the gap blank.
  1. 18 minutes 20 seconds × 2 =
    =  minutes  minutes
  2. 22 minutes 14 seconds × 4 =
    =  minutes  seconds
  3. 25 minutes 25 seconds × 4 =
    =  minutes  seconds
  4. 33 minutes 28 seconds × 11 =
    =  minutes  seconds

Answer. Five lessons will take  hours  minutes.

Answer. The tap will take  hours  minutes to fill four such tanks.