Direct Multiplication 191
Now we multiply crossways: 3 × 6 and 7 × 4, and then multiply the
answer by 10.
3 × 6 = 18
7 × 4 = 28
18 + 28 = 46
46 × 10 = 460
Our subtotal was 2,100. To this we add 400, then we add 60.
2,100 + 400 = 2,500
2,500 + 60 = 2,560
We are nearly there. Now we multiply the units digits, and add.
4 × 6 = 24
2,560 + 24 = 2,584
Try doing the problem yourself in your head. You will fi nd it is
easier than you think. Calculating from left to right means there are
no numbers to carry.
Th e calculation is not as diffi cult as it appears, but your friends
will be very impressed. You just need to practice shrugging your
shoulders and saying, “Oh, it was nothing.”
If you can’t fi nd an easy way to solve a problem using a reference
number, then direct multiplication might be your best option.
DIRECT MULTIPLICATION
USING NEGATIVE NUMBERS
I debated with myself whether this section should be included in the
book. If you fi nd it diffi cult, don’t worry about it. Try it anyway. But
you may fi nd this quite easy. It involves using positive and negative
brent
(Brent)
#1