Akal Pintar

和至少一万 = jumlah sekurang-kurangnya 10 000 最小的五位数是 10 000。所以两个四位数的和，只要等于或大于 10 000，就是五位数。我们可以先想一想：千位的两个数字加起来大约要满 10。 例子：5 600 + 4 400 = 10 000，刚好是最小的五位数，也符合条件。 注意：两个数都必须是四位数，不能用五位数。

the total must be at least 10 000 = jumlah sekurang-kurangnya 10 000 The smallest five-digit number is 10 000, so the sum of the two four-digit numbers must be 10 000 or more. A quick way to think about it: the two thousands digits should add up to about 10. Example: 5 600 + 4 400 = 10 000, exactly the smallest five-digit number, so it works too. Watch out: both numbers must have four digits, not five.

看千位 = lihat digit ribu 判断的窍门是看两个数的千位数字：加起来满 10，和一定是五位数；加起来是 9，要看百位有没有进位上来；加起来 8 或更少，和一定还是四位数。 例子：3 700 + 6 500：千位 3+6=9，百位 7+5=12 进 1，所以和是 10 200，是五位数。 注意：千位加起来是 9 时最容易判断错，一定要检查百位。

look at the thousands digits = lihat digit ribu The trick is to look at the thousands digits. If they add to 10 or more, the sum is surely five digits. If they add to 9, check whether the hundreds carry 1 into the thousands. If they add to 8 or less, the sum still has four digits. Example: 3 700 + 6 500: thousands 3 + 6 = 9, hundreds 7 + 5 = 12 carry 1, so the sum is 10 200, a five-digit number. Watch out: when the thousands add to 9, check the hundreds carefully.

检查三组 = semak tiga pasangan 题目给出三组四位数加法，要找出和是五位数的那一组。窍门是先看两个千位数字的和：满 10，和一定是五位数；是 8 或更少，和一定是四位数；刚好是 9，就要看百位相加有没有进位上来。必要时把整组加出来确认。 例子：6 200 + 3 900：千位 6 + 3 = 9，百位 2 + 9 = 11 进 1，所以和是 10 100，是五位数。 注意：和很接近一万、但还没到一万的，仍然是四位数；千位和是 9 的那一组最容易判断错。

check the three pairs = semak tiga pasangan Which pair of four-digit numbers has a five-digit sum? Add the two thousands digits first: 10 or more means five digits, 8 or less means four digits, and exactly 9 means you must check whether the hundreds carry 1. Add the whole pair if you are unsure. Example: 6 200 + 3 900: the thousands give 6 + 3 = 9 and the hundreds 2 + 9 = 11 carry 1, so the sum 10 100 has five digits. Watch out: a sum just below ten thousand still has four digits, and pairs whose thousands add to 9 are the trickiest.