Counting > Pascal's triangle
1234Pascal's triangle

Solutions to the exercises

Exercise 1
a

( 10 3 ) = 120

b

2 10 = 1024

c

( 10 8 ) + ( 10 9 ) + ( 10 10 ) = 56

d

1024 [ ( 10 9 ) + ( 10 10 ) ] = 1013

Exercise 2
a

Draw grid.

b

( 5 2 ) = 10

c

32

Exercise 3
a

( 14 4 ) = 1001

b

( 10 2 ) = 45

Exercise 4
a

1 - 0, 2 - 0, 2 - 1, 3 - 1, 4 - 1, 4 - 2, 4 - 3, 5 - 3, 6 - 3, 6 - 4.

b

210

c

40

Exercise 5

11 routes.

Exercise 6
a

2 5 = 32

b

30

c

There are exactly ( 5 2 ) = 10 possibilities:
1: - - — — —
2: - — - — —
3: - — — - —
4: - — — — -
5: — - - — —
6: — - — - —
7: — - — — -
8: — — - - —
9: — — - — -
0: — — — - -

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