In the first video (below), we "break apart" three-digit numbers — for example, we write 548 as the sum 500 + 40 + 8 (expanded form). Then we also practice this concept backwards, "forming" or "building" numbers from their parts. For example, we write the sum 60 + 800 as the number 860.
Lastly, we solve some simple missing number questions — and even one really puzzling one!
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In this second video, we place three-digit numbers on a number line. We also find which number is one more/less, two more/less, or ten more/less than a given number.
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Add and subtract multiples of ten from 3-digit numbers (mental math)
Math Mammoth Grade 2 curriculum