96 Speed Math for Kids
Here we have to multiply –6 by 3½. To do this, simply multiply 6 by
3, which is 18, then add half of 6, which is 3, to get 21.
(100 × 3½) 94 × 345 =
–6
–5
–21
Subtract 21 from 345. Multiply the result by 100, then multiply
the numbers in the circles, and then add these two results for our
answer.
345 – 21 = 324
324 × 100 = 32,400
6 × 5 = 30
32,400 + 30 = 32,430 Answer
Th e completed problem looks like this:
(100 × 3½) 94 × 345 = 32,400
–6
–5
- 30
–21 32,430 Answer
USING FACTORS EXPRESSED AS DIVISION
To multiply 48 × 96, we could use reference numbers of 50 and
100, expressed as (50 × 2) or (100 ÷ 2). It would be easier to use
(100 ÷ 2) because 100 then becomes the main reference number. It
is easier to multiply by 100 than by 50.
When writing the multiplication, fi rst write the number that has
the main reference number, so instead of writing 48 × 96, we would
write 96 × 48. Th e completed problem would look like this: