Page 169 - NUMINO Challenge_D2
P. 169
Answer
Key
Type 15-1 Finding the First Number p.130~p.131 Problem solving
1 14, 22, 41 1 Draw a table and work backwards.
2 1st Step 2nd Step 3rd Step Step Number of lollipops
ABC
39 3 9 27 Last Step 120 120 120
27 Before step 60 120 180
Before step 60 210 90
93 Before step 165 105 90
89 8 9 14 2 Before a coin was taken out for the 100th time,
72
41 4 there were (2 1) 2 2 coins in the piggy bank.
98 If you work backwards using this method, you
22 will notice that before and after the coins were
taken out, there were always two coins that
3 39, 93, 89, 98 remained.
Problem solving Creative Thinking p.134~p.135
1 If you work backwards such that the result 1 Blue Marble Red Marble
becomes 11, the calculation is as shown below. Last Step 20 20 15 5
11 3 33 9 42 3 14 8 6 First Step 40 20
Therefore, you need to put 6 as the first number. 2 Make a drawing as shown below and work
2 The 2-digit numbers in which the two digits add backwards.
up to 2 are 11 and 20. Also, the 2-digit numbers before passing
in which the two digits add up to 11 are 29, 38,
47, 56, 65, 74, 83, and 92. ֫ ݫthrough first door:
(10 1)×2 22
1 coin
before passing coins taken by guard
Type 15-2 Give and Take p.132~p.133 ֫ ݫthrough second door: 1 coin
(4 1)×2 10 coins taken
1 A: 20 marbles, B: 20 marbles, C: 80 marbles by guard
before passing
1 coin
֫ ݫthrough third door: coins taken
(1 1)×2 4
by guard
coins left 1 coin
2 Number of Marbles 22 coins
ABC
Step 40 40 40
20 20 80
Last Step 10 70 40
Before step 65 35 20
Before step
Before step
3 A: 65 marbles, B: 35 marbles, C: 20 marbles
NUMINO Challenge D2
Key
Type 15-1 Finding the First Number p.130~p.131 Problem solving
1 14, 22, 41 1 Draw a table and work backwards.
2 1st Step 2nd Step 3rd Step Step Number of lollipops
ABC
39 3 9 27 Last Step 120 120 120
27 Before step 60 120 180
Before step 60 210 90
93 Before step 165 105 90
89 8 9 14 2 Before a coin was taken out for the 100th time,
72
41 4 there were (2 1) 2 2 coins in the piggy bank.
98 If you work backwards using this method, you
22 will notice that before and after the coins were
taken out, there were always two coins that
3 39, 93, 89, 98 remained.
Problem solving Creative Thinking p.134~p.135
1 If you work backwards such that the result 1 Blue Marble Red Marble
becomes 11, the calculation is as shown below. Last Step 20 20 15 5
11 3 33 9 42 3 14 8 6 First Step 40 20
Therefore, you need to put 6 as the first number. 2 Make a drawing as shown below and work
2 The 2-digit numbers in which the two digits add backwards.
up to 2 are 11 and 20. Also, the 2-digit numbers before passing
in which the two digits add up to 11 are 29, 38,
47, 56, 65, 74, 83, and 92. ֫ ݫthrough first door:
(10 1)×2 22
1 coin
before passing coins taken by guard
Type 15-2 Give and Take p.132~p.133 ֫ ݫthrough second door: 1 coin
(4 1)×2 10 coins taken
1 A: 20 marbles, B: 20 marbles, C: 80 marbles by guard
before passing
1 coin
֫ ݫthrough third door: coins taken
(1 1)×2 4
by guard
coins left 1 coin
2 Number of Marbles 22 coins
ABC
Step 40 40 40
20 20 80
Last Step 10 70 40
Before step 65 35 20
Before step
Before step
3 A: 65 marbles, B: 35 marbles, C: 20 marbles
NUMINO Challenge D2
