ffirs.indd

160 Speed Math for Kids
Th e next step would be to multiply 4 times 2 to get 8.
We subtract 8 from our remainder, which is 0, so we end up with a
negative answer. Th at won’t do, so we drop our last digit of the answer
by 1. Our last digit of the answer is now 3, with 3 remainder.
32
–2
1 3. 4 3
30 41 3.^202030
Th ree times 2 is 6, subtracted from 30 leaves 24. Twenty-four
divided by 3 is 8 (with 0 remainder). We need a remainder to
subtract from, so we drop the 8 to 7 with 3 remainder. Th e answer
now becomes 13.437. Because we want an answer correct to
two decimal places, we look at the third digit after the decimal.
If the digit is 5 or higher, we round off upward; if the digit is less
than 5, we round off downward. In this case the digit is 7, so we
round off the previous digit upward. Th e answer is 13.44, correct
to two decimal places.
ESTIMATING ANSWERS
Let’s divide 32 into 240. We set up the problem as before:
32
–2
30 240
We begin by dividing both numbers by 10. Th en, 3 divides into 24
eight times, with 0 remainder. Th e 0 remainder is carried to the next
digit, 0, making a new working number of 0. We adjust for the 2
in 32 by multiplying the last digit of our answer by the 2 in 32 and
subtracting from our working number, 0. Eight times 2 is 16. Zero