30×7

30×7 is the product of the integers 30 and 7, equal to 210 in base-10 arithmetic. It can be computed quickly by noting that 30×7 = (3×7)×10 = 21×10 = 210, or simply by multiplying 7 by 30.

Prime factorization of 210 is 2×3×5×7, the product of the first four prime numbers. This makes 210 the primorial of 7 (written as 7#). It is also a triangular number, specifically the 20th triangular number, since 20×21/2 = 210. The divisors of 210 include 1, 2, 3, 5, 6, 7, 10, 14, 15, 21, 30, 35, 42, 70, 105, and 210.

In other representations, 210 is 11010010 in binary, D2 in hexadecimal, and CCX in Roman numerals.

Applications of 30×7 appear in basic arithmetic education and practical counting problems. For example, multiplying 30 items by 7 groups yields 210 total items. Recognizing the factorization 2×3×5×7 can aid in divisibility checks and factorization tasks, and the fact that 210 is a triangular number connects it to a family of numbers countable as dots arranged in a triangular lattice.

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