2-min Fluency Warm-up — Mental math: add/subtract 100.
200 + 100 =
500 − 100 =
300 + 100 =
700 − 100 =
New Skill: 3-Digit Addition
Adding 3-digit numbers is just like adding 2-digit numbers — you add ones, then tens, then hundreds.
245 + 132
Ones: 5 + 2 = 7
Tens: 40 + 30 = 70
Hundreds: 200 + 100 = 300
Answer: 377
314 + 253
Ones: 4 + 3 = 7
Tens: 10 + 50 = 60
Hundreds: 300 + 200 = 500
Answer: 567
Add using columns. No regrouping needed yet!
Number Talk — Estimate each sum by rounding to hundreds.
342 + 218
Estimate (About 300 + 200 = 500):
Actual:
615 + 281
Estimate (About 600 + 300 = 900):
Actual:
Read carefully. These are big numbers!
The library has 342 books about animals and 218 books about space. How many books are there altogether?
Draw or write your thinking:
books