Lesson 5 – Multiplying Three Digit Numbers By One Digit Numbers

Objective:

• At the end of this lesson, students should be able to multiply three digit numbers by a one digit number.

Example 1

Multiply 142 x 2

Solution

Start from your right hand side as usual. 2 times the 2 in the units column.

2 x 2 = 4        ,           2 times 4 tens gives you 8 tens.

Write 8 in the tens column.

2 x 1 = 2        ,           2 times 1 Hundred gives you 2 Hundreds.

Write 2 in the Hundreds column.

Your answer becomes 284.

Example 2

Multiply 674 by 3

Solution

Multiply 3 by 4 to get 12. Write down the last digit of 12, which is 2, in the units column. You carry 1 forward to the Tens place.

Multiply 7 tens by 3 to get 21 tens.

Add the 1 you carried forward to 21 tens to get 22 tens. 22 tens is 2 hundreds and 2 tens.

Write 2 in the tens column and carry 2 forward to the Hundreds place.

3 x 6 hundreds is 18 hundreds, add the 2 which has been carried forward to the 18. This becomes 20 hundreds which is 2 thousands and 0. Write 0 in hundreds column and 2 in the thousands place.

Your answer becomes 2022.