Write 700 + 20 for a seven-year-old and the most common answer is 900. The 2 slid under the 7, and the tens became hundreds without anyone noticing. This 2nd grade mixed 10s and 100s sums worksheet is made to catch that slip early. Fifteen sums sit in three columns on grid paper, and the numbers keep changing size: 20 + 30 sits right next to 700 + 20, while 500 + 470 waits near the bottom. A girl holding a bunch of cherries watches from the corner. Every number is one of the multiples of 10 or of 100, set out as column addition. A second page gives the answer key.