Step by step
The question
Question: work out 6 × 98 in your head.
6 × 98
1 Split the number
98 is close to 100: it is 100 minus 2.
Round numbers are easy to multiply.
= 6 × (100 − 2)
2 Times each part
The 6 in front of the bracket multiplies every part inside.
6 times 100, minus 6 times 2.
= 6 × 100 − 6 × 2
This is the distributive property.
a × (b − c) = a × b − a × c
distributive property
Careful!
The 6 multiplies both parts.
Not only the 100.
Careful: not 6 × 100 − 2 ✗
3 Work it out
6 times 100 is 600.
6 times 2 is 12.
= 600 − 12
600 minus 12 is 588.
= 588
4 Check
Let's check with the other split: 98 is 90 plus 8.
540 plus 48 is 588 again.
So the answer is right!
6 × 90 + 6 × 8 = 540 + 48 = 588
Let's look back.
First: split the number.
Then: times each part.
Then: work it out.
Last: check.
Answer
= 588