21978
7
The 4 times table will show that a number is divisible by 4. Therefore, times any number, odd or even, by 4: the answer will be divisible by 4.
How about: 1 times 91 plus 4 = 95 or 7 times 13 plus 4 = 95
23
87912 = 4 x 21978
2178
Reverse the operations. Start with 19, subtract 4, which leaves 15. Divide 15 by 3, and that is the number you began with.
The number is 21978. 21978 when multiplied by 4 which gives the result 87912 which is in reverse order.
21978
00000
44444
Try the reverse. 4 times 5 equals what? What=X. Problem:X/4=5. Multiply both sides by 4. 4X/4=4*5(4/4=1, it goes away). X=20
18 is a solution to the equation 4 plus 7 times a number where the result is 9 times that number.
7
It is the same as trebles. Start with how many selections there are and then times by the next number in the sequence and times that by the next number. Then divide that number by 1x2x3. For example 5 selections 5x4x3 =120 / 1x2x3 =6 = 20 trebles in 5 selections. But because it is a reverse forcadt you need to then times that by 2
the sum of 8 and 4 times a number is 36