L2 · The value of each digit; composing numbers many ways
“I can write a number in expanded form, build a number back from its expanded form, and compose the same number in different ways by trading between places - including decimals to thousandths.”
Write 6,304,518 in expanded form. Step 1 (digit by digit, left to right): 6 is 6,000,000; 3 is 300,000; 0 - skip (a zero digit adds nothing); 4 is 4,000; 5 is 500; 1 is 10; 8 is 8. Step 2 (write the sum): 6,304,518 = 6,000,000 + 300,000 + 4,000 + 500 + 10 + 8. Step 3 (refold to check): 6,000,000 + 300,000 = 6,300,000; + 4,000 = 6,304,000; + 500 = 6,304,500; + 10 = 6,304,510; + 8 = 6,304,518. The zeros in the number are the places that contribute no addend - but they still hold their columns in standard form.
The zero in 6,304,518 produces no addend in expanded form because...
Write 2,450,706 in expanded form -> 2,000,000 + 400,000 + 50,000 + 700 + 6
"9,000,000 + 80,000 + 300 + 5 = ___" -> 9,080,305
10 scored questions with a 3-rung hint ladder. Mastery needs 8/10 plus both gate questions.