Product predicted: 6
If an even number is multiplied by 6, the answer will end with the same digit. The number in the ten’s place will be half the number in the one’s place
For Example: 6 × 8 = 48
Exception: 6 multiplied by any multiple of 10.
Catch: 11
There is a quick way to multiply two-digit number by 11 in your head
1. Split the two digits in your mind
2. Add the two digits together
3. Place the number from step 2 between the two digits. If the number from step2 is greater than 9, place the one’s digit in the space and carry the ten’s digit.
For Example: 71 × 11 = 781
• If the sum of the two digit is greater than 9 :
For example: 85 × 11 = 8_5
8 + 5 = 13
Then put 3 in the space and add 1 to the 8 to get 935
THINGS TO REMEMBER BEFORE DIVISION
• If the last digit is a multiple of 2 then the number is divisible by 2
e.g: 46 since 6 is a multiple of 2
• If the sum of the digits is divisible by 3, the whole number is divisible by 3
e.g: 31221 since sum of there digits is 9
• If the last 2 digits are divisible by 4 then the whole number is divisible by 4
e.g: 3452 since 52 is divisible by 4
• If the last digit is 0 or 5, the number can be divided by 5
e.g: 3450 or 3465 since they have 0 and 5 as their last digits respectively
• If the number is applicable for both rule 2 and 3 then it is divisible by 6
e.g: 1236 since their sum is 12 (divisible by 3) and the last digit is a multiple of 2
• If the sum of the digit is divisible by 9 then the number is divisible by 9
e.g: 92754 since sum of their digits is 27 and thus, divisible by 9
• If a number ends with 0 then it can be divided by 10
e.g: 2340 since it ends with 0
• The number is divisible by 12 if the number passes the rules for divisibility by 3 and 4
e.g: 23136 since the sum of their digits is 15 (divisible by 3) and their last 2 digits, i.e 36 is divisible by 4