Math Trick #3-Double Checking

This trick is also simple, like Math Trick #2, but may be hard to understand. If you are trying to find an equivalent fraction, this might help, but this will only work if one of the fraction's numerator and denominator are 1 piece apart, like 1/2. 1 is only one away from 2. Then, the number you multiply by to get the numerator/denominator will be how far away the numbers are in the equivalent fraction. Take an easy fraction such as 2/3. Notice how the numerator and denominator are only one piece apart. Then if you were to find a equivalent fraction by multiplying by 3, you can use this trick. 2 x 3= 6 and 3 x 3= 9, so the equivalent fraction would be 6/9. If you wanted to double check, you can see 9-6= 3, and 3 is the number you multiplied by. This will work every time if you are finding a equivalent fraction, and one of the fraction's numerator and denominator are 1 apart.

Another Example:
3 x 5 = 15
4 x 5 = 20           20-15= 5      5 is the number we multiplied by.