Page 143 - NUMINO Challenge_B2

Answer
Key

4 When 9 is in the thousands place: 5 4 3 60 3 400 200 2 100 is the sum of 200 and 100
times 2.
numbers can be made. There are 1 100 101 even numbers.
When 8 is in the thousands place and 9 is in the
hundreds place: 4 3 12 numbers can be made. 4 199 1 2 99 is the sum of 1 and 99 times 2.
When 8 is in the thousands place and 6 is in the Therefore, there are 1 99 100 odd numbers.
hundreds place: 4 3 12 numbers can be made.
When 8 is in the thousands place and 4 is in the 5 : 91, : 101, : 100
hundreds place: 4 3 12 numbers can be made.
When you add all the 4-digit numbers found Problem solving
above, you get 96 numbers. Therefore, the 97th
number is 8196, the 98th is 8194, the 99th is 8190 1 There are 150 55 1 96 numbers from 55 to
and the 100th is 8169.
150. Therefore, the sum of consecutive numbers
2 Adding by Grouping p.16~p.17 is (55 150) 96 2 9840.

Example 7 8 99 2 Since 191 11 2 90, there are 1 90 91
321
12345 100 100 100 odd numbers from 11 to 191. Therefore, the
99 98 97 96 95 sum of consecutive numbers is
100 100 100 100 100 (11 191) 91 2 9191.

99 terms Type 2-2 Grouping into Interesting Shapes p.20~p.21
1
100, 99, 100, 99, 9900
9900, 4950 89
17
TryItAgain (1 70) 70 2 2485

Example 13

13 13 13 13 13 13 13 13 7 2 ( 8) ( 9) ( 17) 182
34 182,
7, 38 38, 49 148
37

Type 2-1 Number of Consecutive Numbers p.18~p.19 3 37

1 (Number of Consecutive Numbers) 4 ( 8) ( 8) ( 9) ( 10) 129
( Last Number First Number ) 1 22 110

2 120 30 1 91 numbers

NUMINO Challenge B2