Answer:
2.5 + 2.5 + 2.5 + 1.25 = 8.75
Step-by-step explanation:
Mental math is doing calculations mentally. It uses numbers that are easy to work with in your head.
They wanted to calculate 35 % of 25.
They reasoned that
35 % = 10 % + 10 % + 10 % + 5 %
(and 5 % is half of 10 %)
So they took 10 % of 25 =2.5, added it together three times, and then added half of 10 % = ½ × 2.5 = 1.25
They got
2.5 + 2.5 + 2.5 + 1.25 = 7.5 + 1.25 = 8.75
