Problem
First name
Roudro and Dylan
School
Gospel Oak Primary School
Country
Age
11
Number Jumble
If you times the first number with 9 you get the answer.
Eg. If you use 42, you add 4+2 which gives you 6. 42-6=36.
4(which is the first digit of 42)x9=36.
Every answer you get the answer is in the multiple of 9.
Here are some answers.
10=1=9
11=2=9
12=3=9
87=15=73
The difference to the number that you get as a result of adding. The difference between them is 9.
The reason that it works is because the 9 times tables goes up 1 in the tens column while it goes down 1 in the units column. The extra digit that you get from each jump of 10 (for example 10 to 20) makes up for the digit in the units column that you loose because of the rule about the 9 times table (up 1 in tens column and down 1 in units column).