某数在三进制中为12120120110110121121,则将其改写为九进制,其从左向右数第l位数字是几?
(1)100﹣98+96﹣94+92﹣90+…+8﹣6+4﹣2(2)1001×1001﹣1001.
3+6+9+…++300+303 1999+999×999 1.24×0.25+124×75 0.8888×6+0.1111×52.
计算:①3×(x+9)=27②16×8﹣7x=23③7.5﹣7.5×0.5﹣2.6×0.8④13.7×6.5+5.9×13.7﹣12.4×3.7⑤50×[(0.2+4.8﹣4.8+0.2)÷2]⑥11.25+21.25+31.25+41.25+51.25+61.25+71.25+81.25.
计算下列各题①×+25%×+0.25× ②[1﹣(+)]÷③9.6﹣11÷7+×4 ④.
计算(能简算要简算)(1) (2)(3) (4).