30 Speed Math for Kids
+25
100 97 × 125 =
–3
One hundred and twenty-fi ve is 100 plus 25, so we put a plus sign
in front of the 25. Ninety-seven is 100 minus 3, so we put a minus
sign in front of the 3.
We now calculate crossways, either 97 plus 25 or 125 minus 3. One
hundred and twenty-fi ve minus 3 is 122. We write 122 after the
equals sign. We now multiply 122 by the reference number, 100.
One hundred and twenty-two times 100 is 12,200. (To multiply
any number by 100, we simply put two zeros after the number.)
Th is is similar to what we have done in earlier chapters.
Th is is how the problem looks so far:
+25
100 97 × 125 = 12,200
–3
Now we multiply the numbers in the circles. Th ree times 25 is 75,
but that is not really the problem. We have to multiply 25 by minus
- Th e answer is –75.
Now our problem looks like this:
+25
100 97 × 125 = 12,200 – 75
–3