"equal in number" is correct and usable in written English.
You can use it to indicate that two or more items are the same amount. For example, "The number of students in each class was equal in number."
Now they are almost equal in number.
Rising and declining stocks were about equal in number on the New York Stock Exchange.
Both the experimental and control groups were equal in number (n=22).
When the two sexes are equal in number, everyone finds a partner and the split is 50-50.
Both major ethnic groups, blacks and East Indians, are about equal in number and coexist without strife.
At Audi's A3 body shop in Ingolstadt, the robots are roughly equal in number to the 800 employees.
The diagram of a partition is obtained by putting down a row of squares equal in number to the largest part, then immediately below it a row of squares equal in number to the next part, and so on.
But I think that in Illinois he had a situation where the exonerations and the executions were about equal in number over the last several years.
The electors, who are equal in number to each state's delegation in Congress, typically award their votes on a winner-take-all basis.
Registered Democrats and Republicans are almost equal in number, and nearly all of the remaining 43percentt of voters are unaffiliated.
Now they will be equal in number and the swing vote will go to a consumer advocate, who is yet to be named.
