three-digit, 16-digit
cardinal, ordinal
even, odd
Houses on this side of the road have even numbers.

binary, decimal
complex, imaginary, irrational, prime, rational, real, whole (mathematics)
negative, positive
random
lucky, unlucky
Many people think 13 is an unlucky number.

winning
the winning numbers in tonight's lottery

correct, right

calculate
add, add together, divide, multiply, subtract, take away
Add all the numbers together, divide by ten, and then take away twelve.

double, triple
crunch
enter, write, write down
pick, think of

in round numbers (esp. BrE)
There were about 150 there, in round numbers.

number crunching (= doing calculations)
There's more to an accountant's job than just number crunching.

big, high
high numbers of unemployed teachers

low
considerable, good, great, high, large, substantial, unlimited
enormous, huge, impressive, incredible, inordinate, overwhelming, staggering, unprecedented, vast
alarming
sheer
record
a record number of responses

disproportionate, surprising
fair, reasonable, significant
We've had a fair number of complaints about the new phone system.

finite, infinite
There are an infinite number of solutions to the problem.

equal
The candidates received an equal number of votes.

maximum, minimum
average, mean, median
adequate, sufficient
insufficient
limited, low, modest, small, tiny
growing, increasing, rising
increased
reduced
declining
actual, exact, precise
Many people have died in the epidemic—the precise number is not known.

certain
indefinite, unspecified
unknown
approximate
fixed, set
final, overall, total
expected
real, true
poll (AmE)

grow in, increase in
Factories had increased in number between the wars.

decrease in, reduce in
increase
The Pentagon increased the number of troops in Iraq to about 145 000.

double
cut, decrease, reduce
control, limit, restrict
calculate, count, determine, estimate, measure, record
Anna counted the number of men standing around outside.

go up, grow, increase, jump, rise
double
decline, diminish, drop, dwindle, fall, fall off
Shark numbers have dwindled as a result of hunting.
Customer numbers have fallen off in the last year.

vary

in number
The paintings, twelve in number, are over 200 years old.

number of
the number of children who wear glasses

a decline in numbers, a drop in numbers
The decline in numbers of young people means that fewer teachers will be needed.

a growth in numbers, an increase in numbers
few in number, limited in number, small in number
Wild dogs are now few in number.

put the number (of sth) at sth
Conference organizers put the number of attendees at around 500.

model, serial
account, credit-card, membership, passport, PIN, reservation, social-security
ID, identification, identity
license (AmE), license plate (AmE), registration (BrE) (= of a car)
flight
page
apartment (esp. AmE), flat (BrE), house, room

assign sth, give sth

at number
We live at number 21.

fax, phone, telephone
home, office, work
wrong
I keep getting the wrong number.

Freephone (BrE), toll-free (AmE)
daytime, evening
emergency
contact

call, dial, phone (esp. BrE), ring (BrE)
get
give sb

be busy (AmE), be engaged (BrE)
be unobtainable (BrE)

exchange numbers
They exchanged numbers and agreed to go out for a drink one evening.

sb's name and number