.number0 {background-image: url('../images/1_30x24.gif');}
.number1 {background-image: url('../images/2_30x21.gif');}
.number2 {background-image: url('../images/3_30x22.gif');}
.number3 {background-image: url('../images/4_30x24.gif');}
.number4 {background-image: url('../images/5_30x24.gif');}
.number5 {background-image: url('../images/6_30x26.gif');}
.number6 {background-image: url('../images/7_30x22.gif');}
.number7 {background-image: url('../images/8_30x22.gif');}
.number8 {background-image: url('../images/9_30x22.gif');}
.eraseButton {background-image: url('../images/erase.gif');}