Which of the following numbers will increase the most in value if the digit 8 is replaced by 9. 1.8470
2.2188
3.15208
4.72086

This is something you will quickly come to recognise easily however the way to work out what is the biggest change is
1.9470 - 1.8470 = 0.1
2.2199 - 2.2188 = 0.0011
3.15209 - 3.15208 = 0.00001
4.72096 - 4.72086 = 0.0001
Therefore the first one is the biggest change

If there are four friends then each would get, 1.25 or 1 1/4. so this is how i solved 5 ÷ 4 = 1.25 . hope this ; )