Page 143 - NUMINO Challenge_C2
P. 143
Answer
Key
Problem solving Problem solving
1 If the number is 2, the numbers that can go 1 1-digit number: 9 numbers
in the are numbers from 00 to 34. 2-digit number: 90 2 180 numbers
Therefore, there are 35 numbers. 3-digit number: 600 (9 180) 411 numbers
If the number is 2 , the numbers that can go Therefore, the number of 3-digit numbers is 411
in the are numbers from 00 to 39. 3 137. Let be the last number.
Therefore, there are 40 numbers. 100 1 137 236.
If the number is 2 , the numbers that can go 2 The number of cards that are used to make 1-digit
in the are numbers from 00 to 99. numbers is 9. From numbers 10 to 99,
(99 10 1) 2 180 number cards are used to
Therefore, there are 100 numbers. make 2-digit numbers. Since there are 200 (9
180) 11 number cards left from the 200 cards,
The digit 2 appears 35 40 100 175 times. three 3-digit numbers can be made and two cards
remain. Therefore, the last 3-digit number that can
2 The only digit that can go in the hundreds place be made is 102 and the remaining two cards are 1
and 0. Therefore, the last number card that be used
in a 3-digit number is 1. Therefore, the digit 1 is 0.
appeared the most.
There are 10 numbers, 51, 61, 71, 81, 91, 101, Creative Thinking p.22~p.23
111, 121, 131 and 141 that have the digit 1 in
the ones place. There are 10 numbers, 110, 111, 1 There are 9 numbers to type from 1 to 9,
112, , 118, and 119 that have the digit 1 in the
tens place. Numbers from 100 to 150 have the 2 90 180 numbers to type from 10 to 99,
digit 1 in the hundreds place; therefore, there 3 900 2,700 numbers from 100 to 999, and 4
are 150 100 1 51 numbers. numbers to type for 1,000; therefore, there are
9 180 2,700 4 2,893 numbers.
The digit 1 appeared 10 10 51 71 times. Since it takes 1 second to type 1 key, it will take
2,893 seconds to type the numbers from 1 to
Type 2-2 Number of Digits (2) p.20~p.21 1,000.
2,893 60 48 r13; therefore, it will take
1 From numbers 10 to 99, there are 99 10 1 48 minutes and 13 seconds.
90 numbers that have two digits. Therefore,
(99 10 1) 2 180 number cards are used.
2 Since 9 number cards are used to make the
1-digit numbers and 180 number cards are used to
make the 2-digit numbers, 300 (9 180) 111
number cards are used to make the 3-digit
numbers.
3 111 3 37 numbers
4 Let be the last number that can be made.
100 1 37 136.
NUMINO Challenge C2
Key
Problem solving Problem solving
1 If the number is 2, the numbers that can go 1 1-digit number: 9 numbers
in the are numbers from 00 to 34. 2-digit number: 90 2 180 numbers
Therefore, there are 35 numbers. 3-digit number: 600 (9 180) 411 numbers
If the number is 2 , the numbers that can go Therefore, the number of 3-digit numbers is 411
in the are numbers from 00 to 39. 3 137. Let be the last number.
Therefore, there are 40 numbers. 100 1 137 236.
If the number is 2 , the numbers that can go 2 The number of cards that are used to make 1-digit
in the are numbers from 00 to 99. numbers is 9. From numbers 10 to 99,
(99 10 1) 2 180 number cards are used to
Therefore, there are 100 numbers. make 2-digit numbers. Since there are 200 (9
180) 11 number cards left from the 200 cards,
The digit 2 appears 35 40 100 175 times. three 3-digit numbers can be made and two cards
remain. Therefore, the last 3-digit number that can
2 The only digit that can go in the hundreds place be made is 102 and the remaining two cards are 1
and 0. Therefore, the last number card that be used
in a 3-digit number is 1. Therefore, the digit 1 is 0.
appeared the most.
There are 10 numbers, 51, 61, 71, 81, 91, 101, Creative Thinking p.22~p.23
111, 121, 131 and 141 that have the digit 1 in
the ones place. There are 10 numbers, 110, 111, 1 There are 9 numbers to type from 1 to 9,
112, , 118, and 119 that have the digit 1 in the
tens place. Numbers from 100 to 150 have the 2 90 180 numbers to type from 10 to 99,
digit 1 in the hundreds place; therefore, there 3 900 2,700 numbers from 100 to 999, and 4
are 150 100 1 51 numbers. numbers to type for 1,000; therefore, there are
9 180 2,700 4 2,893 numbers.
The digit 1 appeared 10 10 51 71 times. Since it takes 1 second to type 1 key, it will take
2,893 seconds to type the numbers from 1 to
Type 2-2 Number of Digits (2) p.20~p.21 1,000.
2,893 60 48 r13; therefore, it will take
1 From numbers 10 to 99, there are 99 10 1 48 minutes and 13 seconds.
90 numbers that have two digits. Therefore,
(99 10 1) 2 180 number cards are used.
2 Since 9 number cards are used to make the
1-digit numbers and 180 number cards are used to
make the 2-digit numbers, 300 (9 180) 111
number cards are used to make the 3-digit
numbers.
3 111 3 37 numbers
4 Let be the last number that can be made.
100 1 37 136.
NUMINO Challenge C2
