Three digit numbers are pretty hard so we’ve decided to put a video off it (see the blog post on partitioning).
125 + 230 =
e.g. of partitioning:
100 + 200 = 300
20 + 30 = 50
5 + 0 = 5
300 + 50 + 5 = 355
That is the meaning of partitioning! 
Great!!!!!!!
Try these. Good luck!
141 + 252 =
364 + 245 =
645 + 254 =
152 + 146 =
Matha Mania 