Saw a Tweet earlier this week:
Absolutely unbelievable scenes as Sarah in Year 6 takes this down in 8 and a half minutes pic.twitter.com/wk2Z8cCXl8— Ashley Booth (@MrBoothY6) February 13, 2017
Wow. Didn't the child do well. And, we really liked the look of the task, so we set about making some of our own. Our class have really enjoyed trying to solve them since. We made an Excel document for creating them and extended it over the four operations.
At the time of writing, we've used multiplication and addition grids with our class. Not sure how useful the subtraction and division versions will be, but they're there if needed.
Find the resources here. Hope it's useful.