
111 111 111 x 111 111 111 = 12345678 9 87654321 

Value of the Pi (3.14159...) is a number that cannot be written as a fraction (eg 1/2 etc.) 

The opposite sides of a dice cube always add up to seven. 

21978 when multiplied by 4 is the same number with digits in reverse order: 21978 x 4 = 87912 

If you add up the numbers 1  100 consecutively (1+2+3+4+5 etc) the total is 5050 

The billionth digit of pi is 9 

142857 is a cyclic number, the numbers of which always appear in the same order but rotate around when multiplied by any number from 1 to 6.
142857 * 2 = 285714, 142857 * 3 = 428571, 142857 * 4 = 571428, 142857 * 5 = 714285, 142857 * 6 = 857142 