```go
package main

import (
	"bufio"
	"fmt"
	"os"
)

func main() {
	reader := bufio.NewReader(os.Stdin)
	writer := bufio.NewWriter(os.Stdout)
	defer writer.Flush()

	var t int
	fmt.Fscan(reader, &t)
	const mod = 1000000007

	for i := 0; i < t; i++ {
		var n, k int64
		fmt.Fscan(reader, &n, &k)
		var ans int64 = 0
		var power int64 = 1
		for k > 0 {
			if k&1 == 1 {
				ans = (ans + power) % mod
			}
			power = (power * n) % mod
			k >>= 1
		}
		fmt.Fprintln(writer, ans)
	}
}
```