Question 16
How many distinct 4-digit numbers are there such that sum of the first three digits is 20 and sum of the last three digits is 17?
Source-language note: the English and Vietnamese texts admit different readings of “distinct.” Both readings are analysed in the solution; the corresponding number is accepted.
Source-language note: the English and Vietnamese texts admit different readings of “distinct.” Both readings are analysed in the solution; the corresponding number is accepted.