Division - useful tips

Question 1

Division of any number by 5 / 20 / 25 / 50
aim to get a multiple of 10 in the denominator

23 / 5 = 46 / 10 = 4.6
multiply the numerator and denominator by 2

183 / 20 = 915 / 100 = 9.15
multiply the numerator and denominator by 5

17 / 50 = 34 / 100 = 3.4
multiply the numerator and denominator by 2

1308 / 25 = 5232 / 100 = 52.32
multiply the numerator and denominator by 4

Question 2

Division of any number by 0.5 / 0.25 / 2.5 / etc

426.45 / 2.5 = 1705.8 / 10 = 17.058
multiply the numerator and denominator by 4

137 / 0.5 = 274 / 1 = 274
multiply the numerator and denominator by 2

Question 3

Division by 3

1 /3 = 0.3333
2 / 3 = 2 * 1/3 = 2 * 0.3333 = 0.6666

1012 / 3 = (1011 + 1) /3 = 337 + 1/3 = 337.3333
1011 is divisible by 3 (its sum of digits = 3)

Question 4

Division of the numbers with decimals

Step 1: if the number of digits after the dot is not the same, re-write the numbers so that the number of digits after the dot is the same

Step 2: multiply the numerator and denominator by 10 / 100 / 1000 as needed

21 / 0.3 = 21.0 / 0.3 = 21 /3 = 7
multiply the numerator and denominator by 10

9 / 0.15 = 9.00 / 0.15 = 900 / 15 = 60
multiply the numerator and denominator by 100

6.4 / 0.2 = 64 / 2 = 32
the number of digits after the dot is the same, so just remove the digit in both and perform a division as if they are integers

0.56 / 1.4 = 0.56 / 1.40 = 56 / 140 = 0.4
multiply the numerator and denominator by 100