For 402, I had a slightly different solution: get the 67 with 75-(4*2). For 103, if you want to use everything: 100/5 * 6 - (8+7+2) For 502, using them all: 100*4 + 9*8 + 6*5
I missed the obvious one for the last one, but one way you can do it is by recognising that 189 is a multiple of 9 (and so also 3): 189 is 63×3. So using the numbers we have: (100 - 25 - (6 × 2)) × 3 = 189
3+4 = 7, 50+1 = 51, 7*51= 357 - 10 -3 = 344 Only way to get an odd is 50/10 for 5 or 8/8 for 717soo 712/8 is 89, which you cuold get with (100-10)*8-8 but then can't do the 5. so that's +6=718, 1 away 7*100 = 700, 4*9 = 36, 700-36-2 = 662