MathChat

How to Multiply Two Teen Numbers — FAST

Ever wondered if there’s a quick way to multiply two numbers in the teens, like:
14 x 17, or 18 x 16?

Turns out, there is. Stick around a minute, and you’ll learn it. Let’s try it for:
18 x 16.

The trick involves doing two operations with the numbers in the ones place of the teen numbers. The numbers in the ones place are 8 (in the ones place of 18) and 6 (in the ones place of 16).

First, ADD the two digits in the ones place.
8 + 6 = 14.

Take that sum, 14, and add it to 10:   14 + 10 = 24.

Tack a zero on to the end. 24 becomes 240. (Keep that number in mind.)

Next MULTIPLY the two digits in the ones place:
8 x 6 = 48.

Now just add this product, 48, to the 240.
240 + 48  = 288.

That’s the answer. This may seem a little tricky and a little weird, at first, but it gets easy after a few times. Trust me …

O.K., fine, don’t trust me. But just try it one more time, with 14 x 17, and see for yourself.

4 + 7 = 11. 11 + 10 = 21.

21 becomes 210.

Then 4 x 7 = 28, and 210 + 28 = 238.

That’s all there is to it.

Now try these:

a) 13 x 16
b) 12 x 17
c) 14 x 19
d) 12 x 19
e) 13 x 14
f) 17 x 18
g) 19 x 17
h) 15 x 19
j) 16 x 17
k) 18 x 19

Answers:

a) 13 x 16 = 208
b) 12 x 17 = 204
c) 14 x 19 = 266
d) 12 x 19 = 228
e) 13 x 14 = 182
f) 17 x 18 = 306
g) 19 x 17 = 323
h) 15 x 19 = 285
j) 16 x 17 = 272
k) 18 x 19 = 342