15-[8³+3²-{8²-(42+2³)-5³}-2²]

1 answer

15-[8³+3²-{8²-(42+2³)-5³}-2²]
keep nibbling away at it from the inside

= 15-[8³+3²-{8²-(50)-5³}-2²]
= 15-[8³+3²-{-111}-2²
= 15-[8³+3²+111-2²]
= 15-[512 + 9 + 111 - 4]
= 15 - 628
= -613