}
				// Count significant digits after the first non-zero digit.
				if sawNonzeroDigit {
					digits--
				}
			}
		}
		if !hasDecimalPoint {
			// Leading digit 0 should contribute once to digits.
			if len(num) == 2 && num[1] == '0' {
				digits--
			}
			num = append(num, '.')
		}
		for digits > 0 {
			num = append(num, '0')
			digits--
		}
		num = append(num, tail...)
	}

	case 'b':
		p.fmt.fmtInteger(v, 2, isSigned, verb, ldigits)
	case 'o', 'O':
		p.fmt.fmtInteger(v, 8, isSigned, verb, ldigits)
	case 'x':
		p.fmt.fmtInteger(v, 16, isSigned, verb, ldigits)
	case 'X':
		p.fmt.fmtInteger(v, 16, isSigned, verb, udigits)
	case 'c':
		p.fmt.fmtC(v)
	case 'q':
		p.fmt.fmtQc(v)
	case 'U':
		p.fmt.fmtUnicode(v)
	default:
		p.badVerb(verb)
	}
}

//	prefix    = "0" [ "b" | "B" | "o" | "O" | "x" | "X" ] .
//	mantissa  = digits "." [ digits ] | digits | "." digits .
//	pmantissa = [ "_" ] digits "." [ digits ] | [ "_" ] digits | "." digits .
//	digits    = digit { [ "_" ] digit } .
//	digit     = "0" ... "9" | "a" ... "z" | "A" ... "Z" .
//
// Unless fracOk is set, the base argument must be 0 or a value between
// 2 and MaxBase. If fracOk is set, the base argument must be one of

	// was even.
	lok := dl0 && fracl == 0 && (mant&1 == 0)
	if !lok {
		dl++
	}
	// We need to remember whether the trimmed digits of 'dc' are zero.
	c0 := dc0 && fracc == 0
	// render digits
	ryuDigits(d, dl, dc, du, c0, cup)
	d.dp -= q
}

// mulByLog2Log10 returns math.Floor(x * log(2)/log(10)) for an integer x in
// the range -1600 <= x && x <= +1600.
//

// in multiprecision binary precisely.

package strconv

type decimal struct {
	d     [800]byte // digits, big-endian representation
	nd    int       // number of digits used
	dp    int       // decimal point
	neg   bool      // negative flag
	trunc bool      // discarded nonzero digits beyond d[:nd]
}

func (a *decimal) String() string {
	n := 10 + a.nd
	if a.dp > 0 {
		n += a.dp
	}
	if a.dp < 0 {

The first step divides n digits by n digits to ensure that it produces only a
single digit.

Each subsequent step appends the next digit from u to the remainder and divides
those n+1 digits by the n digits of v, producing another quotient digit and a
new n-digit remainder.

Subsequent steps divide n+1 digits by n digits, an operation that in general
might produce two digits. However, as used in the algorithm, that division is

		return 0, 10, nil
	}

	// sign
	var digits []byte
	ch, err = r.ReadByte()
	if err == nil && (ch == '+' || ch == '-') {
		if ch == '-' {
			digits = append(digits, '-')
		}
		ch, err = r.ReadByte()
	}

	// prev encodes the previously seen char: it is one
	// of '_', '0' (a digit), or '.' (anything else). A
	// valid separator '_' may only occur after a digit.
	prev := '.'
	invalSep := false

			prec = digs.nd
		}
	} else if fmt != 'f' {
		// Fixed number of digits.
		digits := prec
		switch fmt {
		case 'e', 'E':
			digits++
		case 'g', 'G':
			if prec == 0 {
				prec = 1
			}
			digits = prec
		default:
			// Invalid mode.
			digits = 1
		}
		var buf [24]byte
		if bitSize == 32 && digits <= 9 {
			digs.d = buf[:]

		{IntLit, "0o60___0", "0o60___0", "'_' must separate successive digits"},
		{IntLit, "0466_", "0466_", "'_' must separate successive digits"},
		{FloatLit, "1_.", "1_.", "'_' must separate successive digits"},
		{FloatLit, "0._1", "0._1", "'_' must separate successive digits"},
		{FloatLit, "2.7_e0", "2.7_e0", "'_' must separate successive digits"},

// digits accepts the sequence { digit | '_' }.
// If base <= 10, digits accepts any decimal digit but records
// the index (relative to the literal start) of a digit >= base
// in *invalid, if *invalid < 0.
// digits returns a bitset describing whether the sequence contained
// digits (bit 0 is set), or separators '_' (bit 1 is set).
func (s *scanner) digits(base int, invalid *int) (digsep int) {