118 Speed Math for Kids
What is 284 minus 68? Let’s subtract 70 from 284 and add 2.
284 – 70 = 214
214 + 2 = 216
Th is is easily done in your head. Calculating with a pencil and paper
involves carrying and borrowing. Th is way is much easier.
How would you calculate 537 minus 298? Again, most people would
use pen and paper. Th e easy way is to subtract 300 and give back 2.
537 – 300 = 237
237 + 2 = 239
Using a written calculation the way people are taught in school
would mean carrying and borrowing twice.
To subtract 87 from a number, take 100 and add 13 (because 100 is
13 more than you wanted to subtract).
432 – 87 =
13
Subtract 100 to get 332. Add 13 (add 10 and then 3) to get 345.
Easy.
Test you rself
Try these problems in your head. You can write down the
answers.
a) 86 – 38 =
b) 42 – 9 =
c) 184 – 57 =
d) 423 – 70 =
e) 651 – 185 =
f) 3,424 – 1,895 =
brent
(Brent)
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