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求方框里的数 = cari pecahan ketiga 先把二分之一换成和其他分数一样的分母。算出前面两个数相减剩多少，再想：还要再减去多少，才会剩下二分之一？这个差就是方框里的数，最后检查能否约简。 例子：7/8 − 1/8 − □ = 1/2 → 6/8 − □ = 4/8 → □ = 2/8 = 1/4。 注意：方框代表“还要减去的部分”，不是剩下的部分。

find the third number = cari pecahan ketiga First write one half with the same denominator as the others. Work out what is left after the first subtraction, then ask how much more must be taken away to leave one half. That difference goes in the box; simplify it if possible. Example: 7/8 − 1/8 − □ = 1/2: 6/8 − □ = 4/8, so □ = 2/8 = 1/4. Watch out: the box is the amount still to take away, not the amount left.

验证 = semak 要判断等式对不对，就把左边真的算出来：把 1 和所有分数都换成同一个分母（这里可以用六），分子从左到右连减，再把结果约简，和右边的二分之一比较。 例子：1 − 1/4 − 1/2 = 4/4 − 1/4 − 2/4 = 1/4，不等于 1/2。 注意：分母不同的分数不能直接用分子相减，要先统一分母。

check it = semak To decide whether the statement is true, actually work out the left side. Write 1 and every fraction with the same denominator (sixths work here), subtract the numerators from left to right, then simplify the result and compare it with one half. Example: 1 − 1/4 − 1/2 = 4/4 − 1/4 − 2/4 = 1/4, which is not 1/2. Watch out: fractions with different denominators cannot be subtracted until they share a denominator.

十二分之几 = per dua belas 题中有二分之一、四分之一和十二分之几，最小公分母是十二。全部换成十二分之几后，先算前两个数的差，再看离二分之一还差多少份，那就是方框里的数；答案记得约简。 例子：9/10 − 1/5 − □ = 1/2 → 9/10 − 2/10 − □ = 5/10 → 7/10 − □ = 5/10 → □ = 2/10 = 1/5。 注意：四分之一换成十二分之几时，分子也要乘三。

in twelfths = per dua belas The question has halves, quarters and twelfths, so the smallest common denominator is 12. After changing everything, find the difference of the first two numbers, then how many twelfths more must go to leave one half. Simplify your answer. Example: 9/10 − 1/5 − □ = 1/2, so 7/10 − □ = 5/10 and □ = 2/10 = 1/5. Watch out: when changing quarters into twelfths, multiply the numerator by 3 as well.