Question

70 decreased by 13% =

Answer 1

If you have a calculator: 
1) To find 1%, divide by 100 (70 / 100 = 0.7) 

2) Then, multiply by the % you need (0.7 x 13 = 9.1) 

Therefore 70 - 9.1 = 60.9 

If you don't have a calculator: 
1) Find 50%, 10%, 5%, and 1%. With these, you can make any % you need. 
50% = X / 2 (= 35) 
10% = X / 10 (= 7) 
5% = first, do 10%, then divide that by 2 (= 3.5) 
1% = X / 100 (= 0.7) 
Where X is the number you want to work out % for 

2) Add those % up to get the amount you want 
10% + 1% + 1% +1% = 13% 
7 + 0.7 + 0.7 + 0.7 = 9.1 

Therefore 70 - 9.1 = 60.9
Hope that helps :)