123_456.123_456;
.123_456;
1_2.1_2e1_2;
1_2.1_2e+1_2;
1_2.1_2e-1_2;
/**************************************************/
123_456.123_456;.123_456;1_2.1_2e1_2;1_2.1_2e+1_2;1_2.1_2e-1_2;
/**************************************************/
123_456.123_456;
.123_456;
1_2.1_2e1_2;
1_2.1_2e+1_2;
1_2.1_2e-1_2;