Grade 1 Math · Level 3, Place Value to 120
Add a Multiple of 10 Within 100
How the lesson starts: Add a Multiple of 10 Within 100
The teddy train
All aboard! Tilly drives the teddy bear train. Each train car carries 10 teddy bears. When cars join the train, we add tens! Let's ride.
Two cars join
34 teddies ride the train. 2 new cars join. That's 20 more teddies! 3 tens and 2 tens make 5 tens. The ones stay 4. 34 + 20 = 54!
Tens go with tens
46 + 30. The 3 in 30 means 3 tens. Add it to the tens. 4 + 3 = 7 tens. The ones stay 6. 76! Watch out! Not 49. Don't add 3 to the ones.