You don't have to solve each one, and you don't even need a calculator if you understand the following rules for integer calculations:
Multiply: only odd*odd will give odd
power: only odd to any power will give odd
Add/subtract: only odd±even will give odd.
Note: for add/subtract, when you have three operands, work out answer in two steps.
Try a few numerical examples for each rule, and you'll have the rules at your disposal for the rest of your math career.
Which one of the following is an even number?
A. 198^7
B. 19x98
C. 19^87
D. 1+9+87
I know I can just solve each one but is there a faster way?
1 answer