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Lesson 1: Place Value 12587654236841 Why is this number hard to read!? 4 538 902 761 For the number above, find and write the digits for the following place values: ten thousands ones thousands ten millions billions hundred millions Take these numbers and write them with the correct spacing… 3412 34125 864312 9004999 60548902 432157809 3412 34 125 864 312 9 004 999 60 548 902 432 157 809 Another student did this: wrote 78939045672 as 789 390 456 72 Is this right? Why or why not? What was this student thinking? Why did he/she make this mistake? • How to avoid this mistake: • Start at the right, draw lines in between every third digit. • ex. 78939045672 78|939|045|672 78,939,045,672 45 3890 2761 What is the place value of the 5? Was it harder to read the place value in the number this way? How is this spacing different from how we usually write a number? We usually group place values by 3’s, (ones, hundreds, thousands), so it’s weird to see it grouped in 4’s. In Japan, however… their place value names look like this: one man oku chou ten ten man ten oku ten chou hundred hundred man hundred oku hundred chou thousand thousand man thousand oku thousand chou man means ten thousand (10 000) what does oku mean?? How about chou??? oku means 100 000, and chou means 1 000 000. This means their place values are grouped by 4’s!! Comparing Values of Digits What does it mean for a number to be so many times another number? 30 is 10 times 3, so 30 is ten times as big as 3. How many times more is the first 3 worth than the second 3? a) b) c) d) e) f) g) h) i) j) k) l) 33 330 3300 33 000 334 507 3 398 412 303 3003 30 003 300 003 342 173 2 356 783 542 a) 10 b) 10 c) 10 d) 10 e) 10 f) 10 g) 100 h) 1000 i) 10 000 j) 100 000 k) 100 000 l) 100 000 How many times more is the 6 worth than the 3? a) b) c) d) e) f) g) h) i) j) k) l) 63 630 6300 63 000 634 507 6 398 412 603 6003 60 003 600 003 642 173 2 642 173 542 a) b) c) d) e) f) g) h) i) j) k) l) 20 20 20 20 20 20 200 200 20 000 200 000 200 000 200 000 How many times more is the 3 worth than the 6? a) b) c) d) e) f) g) h) i) j) k) l) 36 360 3600 36 000 364 507 3 698 412 306 3006 30 006 300 006 342 176 2 342 176 542 a) b) c) d) e) f) g) h) i) j) k) l) 5 5 5 5 5 5 50 500 5000 50 000 50 000 50 000