For practicing some math skills like simple addition, there is just nothing more effective than a pencil and paper. These math worksheets start with simple addition (one-digit) math facts and progress to adding 2-digit numbers in columns. No regrouping is included in out grade 1 exercises.
I have seen a lot of kids quickly pass off their 2’s, 5’s, and 10’s. These tables have an obvious pattern and are much easier to learn. Then there is a serious slow down as kids hit the 3’s, 4’s, and 6’s. By the time they get to the 7’s, 8’s, and 9’s they’ve decided that multiplication is way too hard, and math isn’t their thing.