1. Mental Math 4 Quarters Make a Dollar
Here’s a trick to impress your friends and amaze your parents.
You only need to remember that four quarters makes a dollar.

2. Multiplying by 25 Just remember – 4 quarters makes a dollar!
11 times 25 is just a sum of 11 Twenty-fives.
If we group the Twenty-fives into groups of 4 we get 2 groups with 3 Twenty-fives left over.
Each group of four Twenty-fives is one hundred, so the product is 275.

3. Multiplying by 25 11 times 25 is just a sum of 11 Twenty-fives.
If we group the Twenty-fives into groups of 4 we get 2 groups with 3 Twenty-fives left over.
Each group of four Twenty-fives is one hundred, so the product is 275.

4. Multiplying by 25 How would you multiply
Four 25’s make 100, so how many groups of 4’s are there in 37?
So let’s try this on the product of 37 and 25.
Since 4 goes into 37 nine times with a remainder of 1,
there are 9 groups of 4 Twenty-fives with 1 Twenty-five left over.
Each group of 4 Twenty-fives is 100, so the answer is 925.
There are 9 groups with one 25 left over, so

5. Multiplying by 25 To multiply 25 by an integer, divide the
integer by 4.
The quotient tells you how many 100’s are
in the answer.
The remainder tells you how many 25’s.
So to multiply a number by 25, you don’t multiply.
Instead, you divide the number by 4 and use the quotient and remainder.

6. Work it out!
Okay, try this one out. Divide 19 by 4 to get the quotient and remainder.
See if you can do it in your head. Press the ‘Next’ button when you’ve got it.

7. Work it out!
Now write down the answer.

8. Work it out!
Tada! Easy as pie.

9. Work it out! This works for negative numbers also.
You know the answers going to be negative, so write down the negative sign.
Now work out 9 times 25.

10. Work it out!

11. Work it out!
Nothing to it.

12. Work it out!
It is difficult to divide 1904 in your head, but if you concentrate you can do it.

13. Work it out!
4 goes into 19 four times with a remainder of three, four goes into 37 times with the remainder of two,
and four goes into 24 six times with the remainder of zero. You do the rest.

14. Work it out!

15. Work it out!
This is tough. However remember that 2 to the 7th is the product of 7 Twos.
So what will be the remainder if you divide 2 to the 7th plus 1 by 4?

16. Work it out!
It’s not that hard after all, is it?

17. Work it out! That’s all for now.
You should make up problems to practice on until you have it down pat.