A similar topic is: 36× 2 1.063× 12.
Multiplication of three digits, hundreds× hundreds = bits× bits, and ten digits are hundreds+bits. For example, the second question: 462× 48 084× 264, 4× 4 = 2× 8, 4+2 = 6.
Similar topics are:143× 31○ 34/kloc-0 /×13.