Ask a seven-year-old what 3 + 5 is, then what 300 + 500 is, and watch their face closely. Some start counting on their fingers again, while others grin because they have already spotted the pattern. This 2nd grade adding multiples of 100 worksheet is built for that second reaction. Fifteen sums sit in three columns on grid paper, each one a pair of whole hundreds set out as column addition. The girl on the swing in the corner keeps the page light. A few totals, like 700 + 800, go past 1,000, so the last sums need care. A second page gives the answer key.