Urgent question please solve and only if you know it please. Most accurate gets branliest and a new follower (me). Step one: round each number.
step 2: add the two 10s, use your Smart second grade strategies.
1) 17+23 ---> ___+___=___
2) 42+37 ---> ___+___=___
3) 9+73 ---> ___+___=___
4) 68+21 ---> ___+___=___
5) 12+81 ---> ___+___=___