Which of these ways of calculating 2.5% of a number are correct? Explain your thinking.
A. Calculate 5%, then divide by 2.
B. Calculate 25%, then divide by 10.
C. Divide by 4, then divide by 10.
D. Calculate 1%, double it, and then add another half of 1%.
I am a Mathematics teacher and I could not provide the right concepts and procedure to solve this to my students...