im stuck (1 Viewer)

[jane1820]

Five-digit numbers can be formed from the digits 2, 3, 4, 5 and 6: How many of these numbers are less than 56 432?

[Cambridge 14B: 21.c]

 

[jane1820]

i know what to but im not getting the right answer which is 95

 

[I AM MUSIC]

72 +23

 

[jane1820]

nah bro too good too good

 

[C2H6O]

Five-digit numbers can be formed from the digits 2, 3, 4, 5 and 6: How many of these numbers are less than 56 432?

[Cambridge 14B: 21.c]

We count options for each digit and multiply:

FIRST DIGIT
can be 2, 3, 4 or 5 but not 6; so 4 options

SECOND DIGIT
can be 2, 3, 4, 5, or 6 but we've already used one up so 4 options

THIRD DIGIT
can be 2, 3, 4, 5, or 6 but we've already used 2 so 3 options

FOURTH DIGIT
can be 2, 3, 4, 5, or 6 but we've already used 3 so 2 options

FIFTH DIGIT
can be 2, 3, 4, 5, or 6 but we've already used 4 so 1 option

TRICK: notice they say LESS than 56432 but not equal to? That means we exclude 56432 as an option (-1)

TOTAL: 4*4*3*2*1-1=95

 

[jane1820]

We count options for each digit and multiply:

FIRST DIGIT
can be 2, 3, 4 or 5 but not 6; so 4 options

SECOND DIGIT
can be 2, 3, 4, 5, or 6 but we've already used one up so 4 options

THIRD DIGIT
can be 2, 3, 4, 5, or 6 but we've already used 2 so 3 options

FOURTH DIGIT
can be 2, 3, 4, 5, or 6 but we've already used 3 so 2 options

FIFTH DIGIT
can be 2, 3, 4, 5, or 6 but we've already used 4 so 1 option

TRICK: notice they say LESS than 56432 but not equal to? That means we exclude 56432 as an option (-1)

TOTAL: 4*4*3*2*1-1=95

Oh thats what im doing wrong minusing the one
thx