果软
来源:学生作业帮 编辑:搜搜考试网作业帮 分类:数学作业 时间:2024/08/19 03:24:30
![](http://img.wesiedu.com/upload/5/37/5373d03e3090111f39d4973d3314db2b.jpg)
![果软](/uploads/image/z/20022236-44-6.jpg?t=%E6%9E%9C%E8%BD%AF)
解题思路: 十位数相同,个位数相加等于10的两位数乘法。
解题过程:
十位数相同,个位数相加等于10的两位数乘法。
11X19=209,12X18=216,13X17=221,14X16=224,15X15=225; 21X29=609,22X28=616,23X27=621,24X26=624,25X25=625;
31X39=1209,32X38=1216,33X37=1221,34X36=1224,35X35=1225; 41X49=2009,42X48=2016,43X47=2021,44X46=2024,45X45=2025;
51X59=3009,52X58=3016,53X57=3021,54X56=3024,55X55=3025; 61X69=4209,62X68=4216,63X67=4221,64X66=4224,65X65=4225;
71X79=5609,72X78=5616,73X77=5621,74X76=5624,75X75=5625; 81X89=7209,82X88=7216,83X87=7221,84X86=7224,85X85=7225;
91X89=9009,92X98=9016,93X97=9021,94X96=9024,95X95=9025。
即当B+C=10时,ABXAC=PQRS,结果中的前两位数PQ=AXA+A=AX(A+1),后两位数RS=BXC,注意如果计算后两位数只得到一位数时,则需在其前面补上一个0凑成两位数,如81X89=7209
最终答案:略
解题过程:
十位数相同,个位数相加等于10的两位数乘法。
11X19=209,12X18=216,13X17=221,14X16=224,15X15=225; 21X29=609,22X28=616,23X27=621,24X26=624,25X25=625;
31X39=1209,32X38=1216,33X37=1221,34X36=1224,35X35=1225; 41X49=2009,42X48=2016,43X47=2021,44X46=2024,45X45=2025;
51X59=3009,52X58=3016,53X57=3021,54X56=3024,55X55=3025; 61X69=4209,62X68=4216,63X67=4221,64X66=4224,65X65=4225;
71X79=5609,72X78=5616,73X77=5621,74X76=5624,75X75=5625; 81X89=7209,82X88=7216,83X87=7221,84X86=7224,85X85=7225;
91X89=9009,92X98=9016,93X97=9021,94X96=9024,95X95=9025。
即当B+C=10时,ABXAC=PQRS,结果中的前两位数PQ=AXA+A=AX(A+1),后两位数RS=BXC,注意如果计算后两位数只得到一位数时,则需在其前面补上一个0凑成两位数,如81X89=7209
最终答案:略