8. Long-term Debt

A summary of Long-term Debt follows:

(Stated in millions)

	Mar. 31,		Dec. 31,
	2018		2017
4.00% Senior Notes due 2025	$	1,742	$	1,741
3.30% Senior Notes due 2021		1,595		1,595
3.00% Senior Notes due 2020		1,594		1,593
3.65% Senior Notes due 2023		1,492		1,492
4.20% Senior Notes due 2021		1,100		1,100
2.40% Senior Notes due 2022		997		996
3.63% Senior Notes due 2022		846		846
2.65% Senior Notes due 2022		598		598
2.20% Senior Notes due 2020		498		498
7.00% Notes due 2038		212		212
4.50% Notes due 2021		134		135
5.95% Notes due 2041		115		115
3.60% Notes due 2022		109		110
5.13% Notes due 2043		99		99
4.00% Notes due 2023		82		82
3.70% Notes due 2024		56		56
0.63% Guaranteed Notes due 2019		-		712
1.50% Guaranteed Notes due 2019		-		603
Commercial paper borrowings		1,700		1,694
Other		557		598
	$	13,526	$	14,875

The estimated fair value of Schlumberger’s Long-term Debt, based on quoted market prices at March 31, 2018 and December 31, 2017 was $13.6 billion and $15.2 billion, respectively.

Borrowings under Schlumberger’s commercial paper programs at both March 31, 2018 and December 31, 2017 were $3.0 billion, of which $1.3 billion was classified in Short-term borrowings and current portion of long-term debt in the Consolidated Balance Sheet.