Question

6道小升初英语数学题，哪位大虾能帮忙解答一下？

1.If I climb a staircase 2 steps at a time, one step is left over. Climbing 3 steps at a time gives 2 steps left over, while climbing 4 at a time gives 3 left over. How many steps are there if there are fewer than 20?（翻译、过程、答案）
2.What is the 100th term in the sequence 0, 2, 6, 12, 20, 30, 42, ... ?（过程、答案）

3.Find the value of this product of 98 numbers: （1-2/3）（1-2/4）（1-2/5）……（1-2/98）（1-2/99）（1-2/100）？（过程、答案）
4.The digit in the ones place of a two --digit number is two more than three times the digit in the tens place. If the digits are reverse, the new number is two less than three times the original number. Find the original number.（翻译、过程、答案）
5.A set of 10 numbers has sum 100. Each number of the set is increased by 20, then multipliedby 20 then decreased by 20. What is the sum of the numbers in the new set? （过程、答案）
6.The areas of the faces of a rectangular box are 84 cm2 , 70 cm2and 30 cm2.The volume of the box in cm3 is____. （过程、答案）

今天6点前按要求回答的悬赏！

Answer 1

1.求除2余1，除3余2，除4余3的数中小于20的数。除4余3的数有7,11,15,19，其中除3余2的只有11
2. 0,=0*1 2=1*2 6=2*3 12=3*4 ……所以第100项 =99*100=9900
3. （1-2/3）（1-2/4）（1-2/5）……（1-2/98）（1-2/99）（1-2/100）=1/3 * 2/4 * 3/5 * 4/6 * 5/7 ......* 94/96 * 95/97 * 96/98 * 97/99 * 98/100= 1/3 * 3/5 * 5/7 ...... * 95/97* 97/99 ) ( 2/4 * 4/6......94/96 * 96/98 * 98/100 )=1/99 * 2/100= 1/49500
4. 个位数比十位数的三倍大2. 如果十位数和个位数互调，新得到的数比原来的数的三倍小2.求原来的数。 满足 个位数比十位数的三倍大2 条件的数有 15 ，28 其中 82=28*3-2，满足条件，故原来的数是28
5. （100+10*20）*20-20*10=5800
6. 设高宽长为abc，则ab=84，ac=70 , bc=30 ab*ac*bc=(abc)平方=84*70*30
体积=abc=根号（84*70*30 ）=429