Solution:

Forty

Solution:

step 3 is wrong

Solution:

18 x 12 ÷ 4 + 5 = 59

Solution:

4

No Of circles in the number.

Solution:

8

Solution:

three positive numbers are 1 2 & 3

1 x 2 x 3 = 6
1 + 2 + 3 = 6

Solution:

zero

6 without head => 0
9 without tail => 0
8 in two halves => 0 & 0

Solution:

7 * ((3 / 7) + 3) = 24

Solution:

Let the sum of nine member (total) =x
and the age of old one=z
so its average 4 yrs before=(x+z)/10.
after 4 yrs let z be replaced by y.
so now avg=(x+4*10+y)/10

now (x+z)/10=(x+40+y)/10
so after solving it found
z=y+40.
so old person is 40yrs older than young one.

Solution:

The number is: 12345679
12345679 * 9 = 111111111
12345679 * 18 = 222222222
12345679 * 27 = 333333333
And so on...